Miniature airplane with balancing weight



June 10, 1952 N; E. WALKER V 2,599,957

MINIATURE AIRPLANE WITH BALANCING WEIGHT Filed Oct. 24, 1947 Neville E.Wa er EV i'i'orgy Patented June 10, 1952 UNITED STATES PATENT OFFICE MINIATURE AIRPLANE WITH BALANCING WEIG Neville E. Walker, Portland, Oreg.

Application October 24, 1947, Serial No. 781,929

6 Claims.

It is common practice at the present time to propel gliders and other forms of miniature airplanes into the air by means of a rubber band, or by some form of elastic medium or other propelling device. The form of miniature plane which ascends to maximum altitude is one which most closely resembles a dart. That is to say, if a miniature airplane is made which has stubby wings and tail structure and little or no angle of attack, it will follow straight-line flight and may readily be propelled into the air. Because of said lack of angle of attack, either by way of angle of incidence of the supporting wings or negative angle of incidence of the elevators, it has no gliding angle and thus will fall like the stick of a skyrocket; If a miniature airplane has proper angle of incidence and it is projected into the air in this fashion, the angle of attack tends tocause it to loop instead of to follow straight-line flight. Also, if such an airplane has a massive head formed thereon in the manner of an arrow, the mass of said head tends to induce straight-line flight like a dart. It has a corresponding disadvantage, however, that when said toy airplane descends, it gives to said toy airplane a dart-like function which overcomes its gliding ability. An ideal arrangement would be one in which such airplane would have a massive weight at its nose, which would tend to induce straight-line flight, but which would become detached at the point of greatest elevation so that the glider would thus be in proper balance to glide according to the characteristics built into it. Such an arrangement, however, is impractical because when the weight and the airplane become separated, it would be necessary to find the twocomponent parts and join them together, or to resupply said airplane with such a massive weight for each flight.

The object of my invention is to provide a miniature airplane of this character which has a massive weight arranged in the nose or forward portion thereof, which may be moved to a position well forward of its center of lift so that it would have the characteristics of a dart. but which weight will be moved to proper balancing position when the toy airplane approaches its point of maximum altitude, and, being thus arranged, will arrange the parts to have a good gliding angle.

A further and more specific object of my invention is to provide an arrangement, such as above described, in which said massive weight is moved from a position well forward of the center of lift to a position coinciding more or less with the center of lift by the action of the air stream, and the movement of said weight will be proportioned somewhat to the velocity of the air stream flowing past said miniature airplane, in flight.

A further and more specific object of my invention is so to devise an organization, as previously described, that the weight will move from a position adjacent the nose to a position adjacent the center of lift during a flight of normal duration, said movement or shifting of said weight being accomplished by the air streaming past the fuselage during the flight of said airplane.

A further and more specific object of my invention is to provide a miniature airplane of the character described, in which the length of travel of said weight and the relative position of said Weight may be adjusted within limits, and thus the flight characteristics of said airplane may be predetermined, because of the control and positioning of said balancing weight.

A further and more specific object of my invention is to provide a structure of this character in which said weight may be arranged in a miniature airplane without affecting substantially its streamlining, which will be inexpensive to manufacture, and will be simple and automatic in its operation.

Further and other details of my invention are hereinafter described with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of a miniature airplane embodying my invention, in which the balancing weight is shown in its forward or noseheavy position, as at the start of a flight, and said weight is shown in dotted outline at the position it will assume when the airplane and said balancing weight are arranged in proper gliding balance;

Fig. 2 is a perspective view of a balancing weight, showing in dotted outline helically wound air tunnels for inducing rotation of said balancing weight;

Fig. 3 is a perspective view of a modification in the form of balancing Weight, in which radially disposed helical fins extend laterally from the periphery of said weight, said weight being shown mounted upon an elongated mounting having a helically wound thread formed thereon.

Fig. 4 is an elevation of a toy airplane embodying my invention as the parts would be arranged at the initiation of a flight, the center of mass and the center of lift being shown diagrammatically; and,

Fig. 5 is a similar view of said toy airplane as the parts would be arranged after said airplane 3 has reached maximum altitude, and the weight has been shifted so that the center of mass is substantially in line with the center of lift and the plane is arranged at proper gliding angle.

A miniature airplane I, adapted for my invention, may be of any type, but preferably is one having a fuselage 2, laterally disposed wings 3, a tail structure including a fixed rudder 4, and horizontally disposed tail members 5. Said airplane should be laterally stable about its longitudinal axis 11-11, and the wings 3 and the horizontally disposed tail members 5 should be so arranged as to have proper incidence so that it will have good gliding characteristics. Such airplane should be made of light material such, for example, as balsa wood, and at its forward end or nose 6, a weight I is normally arranged so that the plane will be nose-heavy as far as dynamic balance is concerned.

The fuselage 2 preferably is provided with an elongated slot 8 extending from a point adjacent the nose 6 to a point beneath the wings 3. Extending longitudinally of said slot is an enlongated mounting 9 for the adjustable balancing weight 10, with which my invention is specifically concerned. Said mounting is made of a fiat piece of wire, twisted about its longitudinal axis so as to define a helical thread. I have found that such type of mounting, thus twisted, is less expensive to construct than a mounting in which said thread is cut or otherwise formed. Said balancing weight preferably is provided with a series of airstream-engaging elements or longitudinal tunnels H, vhich extend longitudinally of said weight and are helically disposed with respect to the longitudinal axis of said weight. Said weight preferably is of cylindrical form and is provided with an axial non-circular hole [2, which closely encompasses the elongated mounting, and thus as said weight is shifted longitudinally of said mounting, it is caused to.turn b .reason of the fact that the helical thread engages said hole l2 and rotates said weight.

When the balancing weight is forward, as is shown in Figs. 1 and 4, the center of mass of said toy airplane, including the mass of the balancing weight l0, lies substantially at the point marked a: in Fig. 4. When it is shifted aft, as is shown in Fig. 5, the center of mass of the entire structure lies substantially at the point marked ac, which is under the leading edge 3a of the wing 3. The center of lift of said wing is shown diagrammatically by arrows in Figs. 4 and 5, respectively. Thus when the weight is forward, it causes the center of mass to lie substantially forward of the center of lift. When the weight i moved rearwardly, as is shown in Fig. 5, it lies so that the center of mass is located only slightly ahead of the center of lift, and thus proper gliding angle is provided for the plane as it moves from its point of greatest altitude.

It is desirable that there be quite a large number of twists of the thread in the elongated mounting 9, so that the balancing weight is caused to revolve many times in moving from the point shown in Fig. l to the point shown in Fig. 5. The balancing weight also should be quite massive, and thus, due to said mass and due to the friction engendered by the number of twists per inch of said elongated mounting, the weight is not suddenly driven rearwardly by the high take-off speed of the toy airplane when it is launched by a rubber band or slingshot. The mass of said balancing weight also introduces a large factor of inertia, which resists sudden rotation of said weight. Thus the airplane is well on its way on it upward flight,. gaining altitude before the weight actually twists under the effect of the air stream, and the toy airplane thus is nose-heavy for the take-01f and for a large portion of its upward flight, when greatest forward velocity is attained. This tends to produce straight-line flight at the start of its upward flight and as it follows alon its course, at maximum velocity. The inertia of said balancing weight causes it to spin as the forward velocity and the relative velocity of the air stream decreases, and thus the balancing weight actually is moved to its rearward position as the airplane loses its forward momentum and as it reaches its point of greatest altitude. Then the weight shift rearwardly until the airplane assumes a good gliding angle for its downward glide. Preferably this is arranged so that the downward glide is in long spiral sweeps, or in a series of interrupted downward glides terminating in sharp short upward climbs.

A modification of the airstream-engaging elements carried by the balancing weight embodied in my invention is shown in Fig. 3, where the balancing weight I3 is shown as a cylindrical weight, as in the first embodiment, but is provided with airstream-engaging elements in the form of laterally extending fins 14, extending more or less radially from the elongated mounting I5. Said fins preferably are inclined or helically wound so as to cause said balancing weight to be rotated on said mounting in the manner similar to that described with relation to the balancing weight ID.

If it is desired not to cause the balancin weight to move between fixed termini,.this may be accomplished by detachably securing clips [6 and H at either or both ends of the elongated mounting 9 or 15. The arrangement of a clip on the forward end of said mounting will limit the degree to which the airplane is originally noseheavy, and the clip I! at the rearward end thereof will limit the degree to which the toy airplane will not be in a more or less fiat gliding angle. The proximity of said clip to each other will limit the length of travel of the balancing weight and the flight characteristics of said airplane, both on ascent and descent. The speed at which the balancing weight'turns on its threaded mounting, and the length of effective travel thereof, may be regulated, also, by varying the tightnessor the stiffness of said mounting. If said mounting is not made quite tight and stiff, it tends to gyrate with the weight, and relative rotation of the balancing weight upon the mounting is thus retarded. The speed at Which the balancing weight traverses the effective length of the mountin may also be regulated by varying the area or inclination of the fin-like airstream-engaging elements (fins) M or the tunnel-like airstream-engaging elements (holes or tunnels) II in the embodiments shown in Figs. 3 and 2, respectively. I deem it desirable, however, to leave the balancing weight and their mountings unaffected and vary the characteristics of the balancing weight in moving from a nose-heavy positionto a balancing position by regulating the length of travel, rather than varying the other factors which I have pointed-out. I have found that said balancing.weightspreferably are made of some light weight metal or alloy, such, for example, as aluminum, which has a substantially greater specific gravity than that of balsa wood, but yet the difference in specific gravity is not so large as to limit the effective size :of said balancing weight with respect to the proportions of the miniature airplane in which said balancing weight is to be mounted.

I claim:

1. A miniature airplane having a two-sided elongated fuselage with a longitudinal slot formed therein and open to both sides thereof, and a balancing weight means mounted for rotation about a longitudinal axis and longitudinally movable within said slot in response to the flow of the airstream past said fuselage during flight, said means including a plurality of helically wound longitudinal airstream-engaging elements the ends of which project laterally into said airstream from both sides of said fuselage.

2. A miniature airplane having an elongated fuselage pierced by a longitudinally extending slot open to the sides thereof, and a balancing weight means mounted for rotation about a longitudinal axis and longitudinally movable within said slot in response to the flow of the airstream past said fuselage during flight, said means including a plurality of helically wound laterally extending and longitudinally elongated vanes the ends of which project into said airstream beyond the open sides of said slot.

3. A miniature airplane having an elongated fuselage pierced by a longitudinally extending slot open to the sides thereof, and a balancing weight means mounted for rotation about a longitudinal axis and longitudinally movable within said slot in response to the flow of the airstream past said fuselage during flight, said means including a plurality of helically wound longitudinal tunnels longitudinally piercing said balancing weight and the ends of which project into said airstream beyond the open sides of said slot.

4. In a miniature airplane of the glider type comprising a fuselage and supporting surfaces rendering said airplane laterally stable about its longitudinal axis, an air responsive, movable balancing weight, an elongated track member defining a path longitudinally of said fuselage which said balancing weight follows, said balancing weight having substantial mass with relation to the remainder of said airplane, and being movable along said path to vary the center of mass of said airplane with respect to the center of lift of said supporting surfaces, thereby to vary the gliding angle of said airplane while in flight, and a helically wound thread constituting said track member, the balancing weight being threaded thereon, said balancing weight having obliquely disposed and helically wound elongated vanes projecting laterally beyond the fuselage thereby to engage the airstream flowing alongside the fuselage when said airplane is in flight, to rotate said balancing weight and to shift it longitudinally along its path.

5 In a miniature airplane of the glider type comprising a fuselage and supporting surfaces rendering said airplane laterally stable about its longitudinal axis, an air responsive, movable balancing weight, an elongated track member defining a path longitudinally of said fuselage which said balancing weight follows, said balancing weight having substantial mass with relation to the remainder of said airplane, and being movable along said path to vary the center of mass of said airplane with respect to the center of lift of said supporting surfaces, thereby to vary the gliding angle of said airplane while in flight, and a helically wound thread constituting said track member, the balancing weight being threaded thereon, said balancing weight having helically wound longitudinal tunnels the ends of which project laterally beyond the fuselage thereby to engage the airstream flowing alongside the fuselage when said airplane is in flight, to rotate said balancing weight and to shift it longitudinally along its path.

6. In a miniature airplane of the glider type comprising a fuselage and supporting surfaces rendering said airplane laterally stable about its longitudinal axis, an air responsive, movable balancing weight, an elongated track member defining a path longitudinally of said fuselage which said balancing weight follows, said balancing weight having substantial mass with relation to the remainder of said airplane, and being movable along said path to vary the center of mass of said airplane with respect to the center of lift of said supporting surfaces, thereby to vary the gliding angle of said airplane while in flight, a helically wound thread constituting said track member, the balancing Weight being threaded thereon, said balancing weight having helically wound airstream-engaging elements the ends of which project laterally beyond the fuselage thereby to engage the airstream flowing alongside the fuselage when said airplane is in flight, to rotate said balancing weight and to shift it longitudinally along its path.

NEVILLE E. WALKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 927,815 Ruppin July 13, 1909 1,010,585 Carter Dec. 5, 1911 1,965,793 Crissey July 10, 1934 2,186,587 Kleinberg Jan. 9, 1940 2,313,948 Lambert Mar. 16, 1943 2,364,821 Ruthven Dec. 12, 1944 

